Microscope imaging system and method for emulating a high aperture imaging system, particularly for mask inspection

Abstract

An optical imaging system for inspection microscopes with which lithography masks can be checked for defects particularly through emulation of high-aperture scanner systems. The microscope imaging system for emulating high-aperture imaging systems comprises imaging optics, a detector and an evaluating unit, wherein polarizing optical elements are selectively arranged in the illumination beam path for generating different polarization states of the illumination beam and / or in the imaging beam path for selecting different polarization components of the imaging beam, an optical element with a polarization-dependent intensity attenuation function can be introduced into the imaging beam path, images of the mask and / or sample are received by the detector for differently polarized beam components and are conveyed to the evaluating unit for further processing.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims priority of German Application No. 10 2004 033 603.2, filed Jul. 8, 2004.BACKGROUND OF THE INVENTION[0002]a) Field of the Invention[0003]The present invention is directed to an optical imaging system for inspection microscopes with which lithography masks can be checked for defects particularly through emulation of high-aperture scanner systems.[0004]b) Description of the Related Art[0005]As object structures continue to decrease in size, increasingly higher image-side numerical apertures of scanner systems are required. However, the incident angles which are therefore also increasingly greater result in vector effects, as they are called, in which tangentially polarized and radially polarized beam components have different intensity distributions. It has been shown that the beam components which oscillate parallel to the incident plane defined by the incidence direction and surface normal of the substrate (s-polari...

AI Technical Summary

Benefits of technology

The present invention is about a solution for inspecting lithography masks using microscopes that can emulate the images of scanner systems. The solution includes an imaging system with high-quality optics that can capture small structures and high-resolution images. The system uses a microscope and a detector to capture images of the mask or sample, which are then processed to detect any defects. This solution can also be used in other optical systems to observe and account for the effects of high-aperture imaging optics. Overall, the invention allows for more accurate and reliable inspection of lithography masks.

Problems solved by technology

When a microscope is used to inspect lithography masks by emulating a scanner system, the occurring vector effects are absolutely necessary for examining the lithography mask because a realistic image of the scanner system cannot otherwise be emulated.

In the inspection microscopes known from the prior art, vector effects were not taken into consideration because the numerical apertures of the imaging systems that were used were less than 1 and vector effects therefore led to a minor error.

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